I don't have filled rear tires. I've been thinking of that.
Consider loading your rear tires as a separate issue.
As you intend building a Three Point Hitch counterbalance, I would put all the weight there. Pound for pound, Three Point Hitch weight, which is CANTILEVERED behind the rear axle, will be more effective than tire ballast on the rear axle. There is really no reason to ballast rear tires too, given your focus on FEL lifts.
With a bare tractor weight of 2,460 pounds and 25 horsepower from an 80 cubic inch engine, you will not benefit from loading rear tires when doing traction intensive Three Point Hich work such as moldboard plowing, box blading, etc. You do not have enough power to spin rear tires doing dirt contact work.
So for FEL work keep all the weight in the removable Three Point Hitch ballast box.
I apply the KISS principle to everything having to do with my tractor. (Keep it simple, stupid.)
My Kubota loader and/or tractor manual has maximum front and rear ballast weights listed. Rear is about 2/3 of the loader lift capacity.
Bruce
It is because the rear axle is the pivot point.
Think of a teeter totter, with you over the center pivot.
Hard to move the teeter totter with weight near the center pivot. Easy to move as you shift weight out.......
Cantilevered weight, as above, to the rear of the rear axle is much more effective pound for pound than weight centered on/over the rear axle which is NOT weight cantilevered.
Over rear axle weight does not leverage front end. Behind rear axle weight DOES leverage front end.
Jeff, regarding:
"Counterbalance with ballasted rear tires will be one figure. With air filled rear tires will be another figure."
You have great experience with tractors, which I respect. Knowledge far exceeding mine. But I don't understand why that would be, so I'm hoping to learn something. If the rear axle is the fulcrum point, and the desire is to not overload the front axle, then it seems adding offsetting weight in the rear to counterbalance weight in the front would not be different regardless of the tire situation? Since the tire has equal surface area (and weight) both ahead of and behind the rear axle, it would not move the center of gravity forward or aft whether the tires were heavy or light?
I understand that more tire weight could improve traction and stability. I don't understand how it could affect needed or desired counterweight?
As for the beet juice, where can you buy it? Is it a dealer only item or can I do it DIY?